TOPIC: idea for a new Crossfade EFFECT

i got an idea for a new crossfade effect, for text and for film to
retrogames fans i think will love this, because its the fade effect the 1980 computer zx-spectrum 48k could do.
48k only had 7 colors, so when they wanted to make some kind of fade out, they had to use only those 7 colors rapidly to do that.
the effetc is something like this example video game :

hi, thanx for the interest!
no need of low res 4bit. the hidef picture is fine. the colour would change just like a filter with the 7 colors.
the only tool i think it would be helpfull it would be to ajust the speed as we like